High contrast imaging has a number of applications including capturing an image when the target is actually trying to blind the observer, and attempting to image reflections close to a bright source. Particular applications considered herein address imaging of planets circling other stars; for example, it may be desirable to image planets in an attempt to discover Earth-like planets which may harbor extraterrestrial life. To find and directly observe planets, one needs to study stars as distant as 10 parsecs. The Earth is 1010 times fainter than the Sun and, from a distance of 10 parsecs, the two are less than a tenth of an arcsecond apart.
An occulter is an opaque or partially transmitting mask that is placed in the field of view of a camera or telescope to throw a shadow of the bright source onto the imaging optic. Occulters have the singular property that they remove most of the radiation from the bright source within a critical radius before it enters the imaging optics. Light from the faint source outside the critical light blocking radius of the occulter then becomes observable by the telescope optic and may be viewed without interference from the bright source.
A space-based occulter can have a flower-like shape with a solid inner disk and shaped petals that occult on-axis starlight. This allows the off-axis light from companion objects, such as a terrestrial planet, to be discerned by a telescope. A known space-based occulter design can be formed from a Kapton® blanket with Kapton® edges. Kapton® is a registered trademark for a polyimide film available from E. I. du Pont de Nemours and Company of Wilmington, Del. The Kapton® blanket structure provides for a readily foldable occulter that can be inserted into a 5 meter diameter fairing for launching and deploying in space. However, since Kapton® has a relatively high coefficient of thermal expansion (“CTE”), such an occulter has been determined to provide unreliable operation due to excessive contraction and expansion of the Kapton® edges.